In, for example, U.S. Pat. No. 4,863,538an arrangement is already known for the production of a three-dimensional product by melting in succession selected parts of a layer of powder applied on a work bench. The arrangement comprises a work bench on which the said three-dimensional product is to be constructed, a powder dispenser which is arranged to apply a thin layer of powder onto the work bench to create a powder bed, an irradiation gun for transmitting energy to the powder whereby melting of the powder takes place, means for guiding the radiation emitted by the irradiation gun over the said powder bed to create a cross-section of the said three-dimensional product by melting parts of the said powder bed, and a control computer in which information about a succession of cross-sections of the three-dimensional product is stored. By melting selected parts of powder layers that have been applied in succession, the three-dimensional product is constructed. The control computer is intended to control means for deflecting the radiation generated by the irradiation gun over the powder bed according to an operating plan which reproduces a predetermined pattern. When the required areas of a layer of powder have been melted according to the operating plan, a cross-section of the said three-dimensional body has been created. A three-dimensional product is created by melting in succession cross-sections that are created in succession in layers of powder that are applied in succession by the powder dispenser.
The arrangement according to U.S. Pat. No. 4,863,538 is designed for the manufacture of three-dimensional bodies in various kinds of material, for example metal or plastic. With certain materials, however, problems arise with unwanted side-reactions. An arrangement has therefore been designed which comprises a casing within which the work bench, powder dispenser and irradiation gun are arranged. Within this casing the pressure is reduced, so that a vacuum arises. In this way, side reactions are avoided.
However, a problem has arisen associated with replenishing powder in the powder dispenser. For replenishing, the vacuum chamber must be opened, powder replenished, the vacuum chamber closed and a vacuum created again. This procedure involves a stoppage in the manufacturing process. In addition, the product on the work bench is able to cool. This means, among other things, that the fusion of the different layers is impaired and that the next layer of powder can therefore adhere less strongly. Cracks can arise in the product.
There is thus a need to solve these problems associated with replenishing the powder in the arrangement.